diff options
Diffstat (limited to 'numpy/lib/format.py')
| -rw-r--r-- | numpy/lib/format.py | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/numpy/lib/format.py b/numpy/lib/format.py index 625768b62..3cebdd173 100644 --- a/numpy/lib/format.py +++ b/numpy/lib/format.py @@ -177,6 +177,8 @@ MAGIC_PREFIX = b'\x93NUMPY' MAGIC_LEN = len(MAGIC_PREFIX) + 2 ARRAY_ALIGN = 64 # plausible values are powers of 2 between 16 and 4096 BUFFER_SIZE = 2**18 # size of buffer for reading npz files in bytes +# allow growth within the address space of a 64 bit machine along one axis +GROWTH_AXIS_MAX_DIGITS = 21 # = len(str(8*2**64-1)) hypothetical int1 dtype # difference between version 1.0 and 2.0 is a 4 byte (I) header length # instead of 2 bytes (H) allowing storage of large structured arrays @@ -431,6 +433,15 @@ def _write_array_header(fp, d, version=None): header.append("'%s': %s, " % (key, repr(value))) header.append("}") header = "".join(header) + + # Add some spare space so that the array header can be modified in-place + # when changing the array size, e.g. when growing it by appending data at + # the end. + shape = d['shape'] + header += " " * ((GROWTH_AXIS_MAX_DIGITS - len(repr( + shape[-1 if d['fortran_order'] else 0] + ))) if len(shape) > 0 else 0) + if version is None: header = _wrap_header_guess_version(header) else: |